Naphtha from fluid coking of residua



April 17, 1956 w. J. MATTox NAPHTHA FROM FLUID coxING oF RESIDUA FiledMay 3l. 195] United States Patent O The present inventionpperta'ins tonanphtha improvement and more particularly to thecatalytic 4reforniingof Yhydrocarbon fractions .boiling within the motor fuel or naphthaboiling range prepared by the fluid coking of .residua to convert saidhydrocarbon fractions ,into motor fuels .of improved stability andcleanliness and lof good antiknock qualit-y. -Speciiically thisinvention'involvestreatment of the-olenic gasline fractionsprorducediinthe fluid coking of residua in the vpresence ofjhydrogentransfercatalysts under hydrogen .transfer `canditions 'to ,effectpartial hydrogenation of dioleiinic and/ or acetylenic compounds ofthe'cracled components. y v

Numereusproesses 'have beenrrenosed for the C011- versvn er reforming ofhydrocarbon fractions 'boiling within the -rnotor .fuel or naphtha,range .t increase the arometipity .anlimprove zthe antiknvsk'-.ehetacteristics of Asaid"hydrocarlmnfractions. Reforming processesemv plenas catalysts, espeially ilyroiorfmns and aromatizmaarewiteiyusein the petrleum instrytoupsrade or hnprovetheanti-"knockcharacteristics of motor 'fuels It "has "also '"beenproposedto subject'naphdreriicpetroleum fractionsto hydrogen -transferwith'normally'liquid olen'ic @hydrocarbons whereby 'the 4rnaphthenicconstituents are converted tol aromatics and fthe` leinic hydrocarbonsareconverted to vvparaflnic zhydrocarbonsby `theihydrogen removedfrom`the naphtlrenicconstituents. A 1

' in viewoff -thegincreasing=dernarfds for greater lvolumes of motorl'fuel {of} improved'fan'tiknolpropertiesberesidum conversion processes4#and catalytic reforming processes have been thesubjectof intensiveinvestigation E'in Janfeff ort to ilind new catalysts ornewy conditionsorft'echques for A'increasing fthe total Vaniuun't Lof motor fuel.produced grading -of nnotor "lfuelmr =naphtha fractions :to increaseyields vanti/'or improve une istability, cleanliness "and anti-l knoekcharacteristics of :the motor `.fuel.p1'oduct.

lt isthe fobiectrof this inventionitorprovideianiimproved` processfforvpreparing :motors-fuels thighyields, tof ,good stability;cleanliness and :anti-knock :properties 'itis falso @the :object .of;tliis .finventionptozprepare motor fuelszinrh'ighyields-.andiwithigoodcstabilityeandr anti-knock properties by av;combined ;.proce'ss iof .coking residua-5in admixtuie iwithfnaphtharbythe fluidi` coking :technique .fand

treating the resultant inaphtha under :hydrogen @transfer l seduced by.was .residual seeks Qn eid, 'sae-f lyticallyinert solids such assanihfpet'roleum cmrlenpuniice' ICC 12' or the like .at-.temperaturesyabove l000 F., preferably between 1050 and `1.150" P. .in thepresenceof substantial proportions, atleast 25% andpreferably about50-75 vol. percent'on tot-al 'hydrocarbon Jfeed of va naphtha boilingwithin Ithe range .of about '1Z0-43,0 F. are. subjected to hydrogentransfer `conditions adequate to Velfect partial hydrogenation.ofdioleiinc fand/ or `acetylenic .compounds of the cracked components.By suitable control tof .the feedstock and cracking .or eoking4Condit-ions it may be possible toiprovide suicient naphthenicclovmpoundsin the `coker reaction products tofobviate vthe necessity ofadding an extraneous ,stream v of naphtha to the .c oker naphtha tofacilitate hydrogen transfer. 'If the Cokerv naphtha is deficient innaphthenic components however, it is advisable to add virginnaphthafcontaining substantialamounts-of naphthenichydrocabons. Ifdesired, one

or ymoreof the'Cz, 'C3 and'Ci fractions of coker reaction products mayybe combinedw'ith the coker naphtha and subjected tothe hydrogentransfer'treatment. The treatment of the coker naphtha is effected attemperatures Vof about 10U-800 P., at pressures of from atmospheric toabout'600 lbs. per sq. inch and in contact with catalysts such as.nickel sulfide, tungsten sulfide, molybdenum'sulde, preferably on asuitable support or one kor more of thechromitesof nickel, cobalt, zinc,copper, magnesium, tin or manganese or a chromia type catalystsuch aschromium oxide on alumina 'or zinc aluminate spinel or there may also'beused a supported palladium or platinum composite containing about-0.01to '2.0 wt. per cent of platinum lor palladium kupon a suitablek supportlsuch as activated alumina, activated charcoal or the like.

Reference is made-to the accompanying-drawing illustratingdiagrammatically'one embodiment of lthe present invention.

In-the drawing l0 is a coking vessel similar to conventional dense bed,'bottom -drawoif lluidized solids contacting-vessels and 'l1-is atransferline'for the introduction of finely/divided solids in admixturewith fluidizing gas or vapors. The transfer Vline discharges into aninlet chamber 12 inthe bottom of coking'vessel '10. The inlet chamber i2comprises van -inverted conical section superposed `by a horizontally`disposed perforatedplate or .grid member L13 whichserves to distributethe incoming solids and -vapors uniformly over theentire-cross sectionofthe coking vessel 10. The colting-vessel is 'charged with finelydivided, substantially inertlsolids such as sand, pumice, petroleumcoke, clay, etc., havingaparticlesize of about 30-400f mesh which are.maintained :as ia dense, -fluidized,

turbulentbed 14 having Va definite @level ..15 or interfaceV separatingthe turbulent bed or dense phase 14 from an upperdilute*orffdisperse'phase .16. Y Linear superiicialrgas velocitiesthrough'the cokingxvessel 10.may be varied b etween about 013 tofabout5.0 ft.-per second toestablish apparent densities ofabout20'to .6,0 lbs.per cu. ft. in dense bed y:154 andfabout 0.00l'to 0 1 lb. per cu.-ft.,in disperse 1 phase 1-6.

A line 17 -isprovi'dedthrcugh .which'residua for coking is supplied-tothecoking vessel"=10. The line 1.7 connects to lsuitable fspray nozzles#mounted on manifoldl or` header 1S arranged inthe upper rparts of the'coking vessel 1i). The-distance of travel of droplets of residuurnthrough the 'disperse phase, i. e., before lcontact with the main bodyofuidized solids or dense bed "14 should be about 5 Ito 20ifeet,prefer-ablyabout 10-feet. Design of the coking vessel andthefuidizing conditions therein should be suchlas lu'lill'perrnit aresidencetirne of theiupflowing vapors Ain-the fdense bed 14`of about'3to 60seconds and descending ktimefor liquid lresiduum droplets throughthe disperse ,phase 16 of `aboutgOzS `to 10 Aseconds depending u ponthedegree 'of dispersion ofthesprayiandthe velocity of upllowing gases. Theliquid -re`siduum ifeed -rate Patented Apr. 17, 195eV may be about 0.15to 3.0 wt./hr./wt. (lbs. of residuum per hour per lb. of solid contactmaterial in the coking vessel). The temperature within the dense bed 14should be maintained at about 1050-1 150 F. by circulation of thecontact solids as will now be described.

Contact solids from the dense bed 14 pass downwardly around inletchamber 12 at the bottom of the coking vessel l to an outlet pipe 20.Stripping gas such as steam may be introduced at i9 to remove entrainedVaporous material from the Contact solids passing to the outlet pipe.Part of thc contact solids passing into outlet pipe may be withdrawnfrom the system through valve controlled discharge line 21 in order tomaintain contact solids inventory at the desired level. The remainder ofthe contact solids pass down through conduit 20, preferablycountercurrent to a stream of steam or other inert stripping ortluidizing gas supplied through one or more taps 22 which serves tomaintain the solid particles in iiuidized condition and removeadditional vaporizable materials from the Contact solids beforeadmixture of said solids with air or combustion gas.

The stripped contact solids are discharged from conduit 20 throughcontrol valve 23 into transfer line 24 where they are picked up by astream of air or combustion gas and conveyed to heater vessel Z5. Thetransfer line 24 discharges the suspension of contact solids in air orcombustion gas into inlet chamber 26 arranged adjacent the bottom ofheater vessel 25. The inlet chamber 26, similarly to the inlet chamber12 in coking vessel 10, comprises an inverted conical section superposedby a horizontally disposed perforated plate or grid 27 which serves todistribute the incoming solids and air uniformly over the entire crosssection of the heater vessel 25. The linear superficial velocity of theair or combustion gas passing through the heater vessel 2S, similarly tothe gas velocities through coking vessel 10, may be varied between about0.3 to about 5.() ft. per second and forms therein a dense, iluidized,turbulent bed 2S of contact solids having a definite level 29 orinterface separating the dense bed from a dilute or disperse phase 36 inthe upper part of the heater vessel 25. The combustion gases arewithdrawn overhead from the heater through a cyclone separator 31 or thelike which serves to separate most of the entrained solid particleswhich may be returned to the dense bed 28 via the dip leg attached tothe bottom of separator 3i.. The combustion gases pass to the atmospherevia stack 32 or; if desired, to heat recovery equipment and thence tothe atmosphere or to storage for use as stripping gas or the like.

in the event that petroleum colte is used as the contact solid, thesolid material withdrawn from the coking vessel 10 and supplied toheater vessel 25 will be essentially 100% colte. ln case a material suchas sand is used as the contact material it is advisable to maintain thecoke content at a relatively high level, for example about 5 to 20 wt.percent at all times in order to maintain good burning rates and toachieve good utilization of the air supplied to the heater vessel 25.The solids leaving the coking vessel 10 will ordinarily have a cokecontent that is about 0.5 to about l0 wt. percent higher than that ofthe solids leaving the heater vessel. This figure depends upon theamount of coke deposited by the particular feed used and the ratio ofsolids circulation rate to oil feed rate. Fluidized solid contactmaterial carrying about 5 to ltl wt. percent of colte may be withdrawnfrom the coiting vessel for circulation to the heater vessel at a rateof about i to l0 times the total oil feed rate to the coking vessel."ihc suspension of withdrawn contact material in air or combustion gaspasses through the transfer line 2d :md distributor plate 27 to lortu adense iluidized bed 2S in which the desired amount of coke is burned oiof the contact particles. As a result of the combustion of the coke,taking place in the transfer line and heater vessel 25, the solidcontact materials are heated to temperatures of about 1150" to l300 F.Ordinarily the temperature of the dense bed of contact material inheater vessel 25 should be at least about 50 higher than the temperatureof the dense luidized bed 14 in colting vessel 1t). About G-6000 cu. ft.of air per bbl. of total feed to the colting vessel will sufice to burnofi all the coke formed and maintain the system in heat balance at theconditions speciiied.

Fluidized solid contact material at the temperature of the dense bed 28is Withdrawn through the standpipe 33 connected to the bottom of heatervessel 2S. The solid contact materials are aerated and/or stripped withsteam or inert gas supplied through one or more taps 34 provided on thestandpipe 33. The reheated contact solids are discharged from standpipe33 through control valve 35 into transfer line 11 where they are pickedup by a stream of fiuidized gas and conveyed to coking vessel 10 atsubstantially the same rate at which the solid particles were withdrawntherefrom so as to supply the heat required in coking vessel 10 assensible heat of the reheated contact solids.

The uidizing gas used to convey the solid contact particles throughtransfer line 11 may be steam or an inert gas but is preferably anaphtha cut since the naphtha is not only improved or upgraded by thetreatment in the coking vessel 10 but more importantly it appears toexert a synergistic etfect on the conversion of the residuum in thecoking operation to form larger amounts of valuable liquid products. Thenaphtha feed stock, which may be a virgin naphtha, a catalyticallycracked naptha, a Fischer- Tropsch naphtha or the like having a boilingrange of between bout and 430 F. is supplied through inlet 37 and may,if desired, be passed through heater coils 38 disposed in the dense bed28 in order to preheat the same prior to its passage via line 39 intotransfer line 11 Where it is mixed with the reheated solid contactparticles or it may be supplied in liquid form to transfer line 11 bymeans of inlet line 40. A further possibility is to utilize naphtha,preheated or not as desired, as the uidizing medium and to supplementits action by the introduction of a second iluidizing medium such assteam through inlet line 40. Upon contacting the reheated contact solidsthe naphtha is vaporized and/or partially cracked to form a limitedamount of normally gaseous hydrocarbons. The feed rate of the naphtha toline 37 is maintained at a rate of about 0.25 to about 4.0 wt./hr./wt.(lbs. of naphtha per hour per lb. of contact solid in the cokingvessel).

Vaporous coldng products containing small amounts of entrained solidparticles pass into the disperse phase 16 in the upper part of cokervessel 10 and pass therethrough countercurrently to descending dropletsof residuum feed. In this way the said residuum feed droplets arepreheated and pretreated to give olf relatively low temperature cokingproducts during their passage through the dilute or disperse phase.Simultaneously the Vaporous coking products are quenched to temperaturesapproximating or somewhat above the temperature of the residuum feedthereby avoiding excessive cracking. At the same time most of the solidparticles entrained with the Vaporous coking products become caught bythe descending liquid droplets and are thereby scrubbed out of thereaction products so that no special solids separation equipment isrequired.

The Vaporous coking products amount to about 90-95 wt. percent on totalfeed and pass overhead from coking vessel 10 through line 42 attemperatures of about 700- 1000 F. into fractionating column 43. About20-30 wt. percent of product gases based on total feed are takenoverhead from fractionator 43 through line 44 for use in accordance withthe present invention as will presently be described. In the event thatthere are excessive amounts of cracked gases available, part of thecracked gases may be withdrawn from the unit and passed to suitableprocessing or recovery equipment.

blended with virgingas oilandpassed to .a-.ca'ta1yt'ic crack`Yingoperation. Coker bottomsk boiling above about 950 F. and `-amountinguto `about .1Q-.10 voLpercent of the .total feed is Awithdrawn'through1ine47 .and passed to ful .oil storage or lblending or, .if\desired,.the bottoms .fraction may tbe .recycled to Athe coking vessel for.retreatment therein. K

The foregoing operations are essentially the same as set out inapplication SerialNo. 182,036, .tiled August 29, 1950, byCharles.N..Kimber1in.etal., now U. S. Patent No. 2,636,844. j

It-has been found-that the-lowerboiling hydrocarbons produced inthecokingof residua as described above contain l'dioleins such -asbutadiene, fpent'a'diene as Well `as higher boiling diolefns --and-while theymay be present in various fractions -in 4appreciablequantities the amounts present 'are =notsuflicient-to-justifytheirseparation. Such materials, however, `are-notdesirable components`of i'feeds to operations-*involving polymerization, falkylation, etc.,and the higher boiling liquid diolelins are notoriously bad gum formersin naphthas or motor fuels. In accordance with this invention thecracked gaseous product and the naphtha cut removed through line 45 arecombined and subjected to a treatment to convert the diolenic and/ oracetylenic components to monoolenic compounds, or what is equivalentthereto, passing a C2-, Ca-, or Ct to 430 F. or lower end point naphthaor gasoline fraction over hydrogenation type catalysts which are activefor hydrogenation of dioleflns to monooleins but which are relativelyinactive for lthe hydrogenation of monoolens to paraliins. If thenaphtha or gasoline fraction is somewhat delicient in naphthenichydrocarbons, i. e., contains less than about 5-15 Vol. percent ofnaphthenes it may be desirable to add a virgin or other naphtha stock tosupply naphthenes for hydrogen exchange.

To effect the desired after treatment of the naphtha, the naphtharemoved through line 4S and the cracked gases taken overhead throughline 44 are combined in conduit 48 after the addition, if desired ornecessary, of a naphthenic naphtha supplied through line 49. Theresultant mixture is then subjected to hydrogen transfer conditions toeffect simultaneous reforming and stabilization.

Suitable catalysts that may be used to effect the selective conversionof the diolelinic and acetylenic components to monooleiins includenickel sulfide, tungsten sulfide, molybdenum sulfide or mixtures ofthese preferably upon a support such as alumina, silica, zirconia,titania, etc. lnstead of said sullides there may be used one lor more ofthe chromites of nickel, cobalt, Zinc, copper, magnesium, tin ormanganese. Chromia type catalysts such as chromia on 'alumina or uponzinc aluminate spine] may also be used. Supported palladium or platinumcomposites containing about 0.01 to 2.0 wt. percent of platinum orpalladium upon a suitable support such as silica get, activated aluminaor activated carbon may be used. In this case it is desirable to addsmall amounts of oxygencontaining materials such as H2O, CO, etc. whichact as mild poisons and inhibit the hydrogenation of mono-olelins toparafins.

Contact of the naphtha and the oleflnic cracked gases with the abovecatalytic agents may be eiected in any desired manner, for example withfinely divided catalyst particles in a fluidized solids reactor systemof the upflow or bottom drawoff type or in a fixed or moving bed or in asuspensoid type operation. Contact of the naphthacracked gas mixturewith the catalyst may be effected at temperatures of Afrom about 100 .toabout 800 F. at pressures"fromatmospheric 'to about `60"0lbs. per sq.inch gauge. The feed rate should Abe within the range of about '0.1 Tto.aboutfO v./v."/hr. -"`('lquid 'volumes .of r'oil per volume Vo'lcatalyst penhour). The `.preferred 'temperature range will be"influenced by catalyst type since the "above-described 'catalysts'will.not always :be equivalent. For example, the lnickel 'sulfidepreparations require utemperatures 'of about 30G-1500". VAF., copperchromite about l100-"650 ii., 'and 'chromia-'containing cornpositesabout 50G-"800' E 'Platinum or palladiumecontaining composites can beused at temperatures of V"from about 100-"750 F.

As shown in the drawing, the mixture of naphtha and cracked gases "ispassed xthrough `'conduit 48. `rCatalyst of the Y'abeve-'mentionedclasses isdischarged from hopper 49 into conduit4'8 in *t'hedesiredamount. The'mixture of catalyst and oil is then'passed Jvia lliney48=through"lreater coils l"50 which l'may'advantageonsly'be Jarrangedin the dense ibedZS within vheater 4ve'sse'l 25. The reaction 'mixture'discharged from heater `4coils -50 i may thenbe passed through cycloneseparatorsror thelike to free 'the hydrocarbon zmaterials of Atheaccompanying catalyst particles. Alternatively a separate treatingvessel could be v'used charged with aiixed :bed of catalyst particlesand the mixture of naphtha and cracked ygases merely pas-sed throughlsuitable Ipreheat'er eoils-arranged in the -heater vessel 25 or in aseparate furnace and -thence through lthe fixed catalyst bed to suitablefractionating equipment.

The following example is illustrative of the present invention:

Example Employing a 2.4% So. La. residuum (11.9 API gravity) a cokingoperation was'carried out in a luidized bed of 100-200 mesh sand at anaverage bed temperature of 1080 F., 1.6 w./hr./w., 14 p. s. i. g., andwith 40 wt. per cent steam diluent. The coke produced amounted to 10 wt.per cent of the residuum feed and the approxi-l mately 90% of gaseousand liquid products was distributed as follows:

The above C4 cut plus C5-430" F. gasoline with about 25 vol. per cent ofa naphthenic straight-run gasoline fraction is contacted with a 10%copper chromite-silica catalyst at 600 F. and atmospheric pressure togive without substantial volumetric losses a stable motor fuel of 90432unleaded research octane number and having less than 1% of dioleins. TheC4 cut low is butadiene but high in total unsaturation (91%) issuitablefor alkylation, polymerization, etc.

The foregoing description contains a limited number of embodiments ofthe present invention. It will be understood, however, that numerousvariations areY possible without departing from the scope of thefollowing claims.

What is claimed is:

l. A method which comprises coking a lpetroleum residuum stock in auidized bed of substantially inert contact material attemperatures ofl000-1200 F. and

Y subjecting a mixture of the reaction products from said coking processboiling below about 430 F., and a naphtha stock rich in naphthenes totreatment in contact with a chromite hydrogenation catalyst etective forthe conversion of dioleiinic and acetylenic compounds to monooleiins butwhich is relatively inactive for the hydrogenation of monoolefins toparatlins thereby selectively converting the dioleiinic and acetyleniccomponents to monoolelins.

2. A method which comprises coking a petroleum residuum stock in -auidized bed of substantially inert contact material in the presence ofsubstantial amounts of added naphtha at temperatures of 1000-1200 F. andsubjecting a mixture of the reaction products from said coking processboiling below about 430 F., and a naphtha stock rich in naphthenes totreatment in contact with a chromite hydrogenation catalyst effectivefor the conversion of diolenic and acetylenic compounds to monoolefinsbut which is relatively inactive for the hydrogenation of monoolens toparains thereby selectively converting the diolenic and acetyleniccomponents to monoolens.

3. A method which comprises coking a petroleum residuum stock in auidized bed of substantially inert contact material at temperatures of100G-1200 F. and subjecting a mixture of the reaction products from saidcoking process boiling below about 430 F., and a naphtha stock rich innaphthenes to treatment in contact with a chromite hydrogenationcatalyst eiective for the conversion of diolefinic and acetyleniccompounds to monoolens but which is relatively inactive for thehydrogenation of monoolens to parafns, at temperatures of from 100 to800 F., pressures of from atmospheric to 600 lbs/sq. in. and at feedrates of from 0.1 to 5.0 v./v./hr. thereby selectively converting thediolenic and acetylenic components to monoolens.

4. A method which comprises coking a petroleum residuum stock in, atluidized bed of substantially inert contact material in the presence ofsubstantial amounts of added naphtha at temperatures of 1000-1200 F. andsubjecting a mixture of the reaction products from said coking processboiling below about 430 F., and a naphtha stock rich in naphthenes totreatment in contact with a chromite hydrogenation catalyst eiective forthe conversion of diolenic and acetylenic compounds to monoolens butwhich is relatively inactive for the hydrogenation of monoolens toparains, at temperatures of from 100 to 800 F., pressures of fromatmospheric to 600 1bs./sq. in. and at feed rates of from 0.1 to 5.0v./v./hr, thereby selectively converting the diolenic and acetyleniccomponents to monoolens.

References Cited in the le of this patent UNITED STATES PATENTS2,206,200 Ocon July 2, 1940 2,283,854 Friedman et al. May 19, 19422,289,716 Marschner July 14, 1942 2,339,246 Bates et al. Jan. 18, 19442,359,759 Hebbard et al Oct. 10, 1944 2,472,254 Johnson June 7, 19492,542,970 Jones Feb. 27, 1951 2,636,844 Kimberlin et al. Apr. 28, 1953

1. A METHOD WHICH COMPRISES COKING A PETROLEUM RESIDUUM STOCK IN AFLUIDIZED BED OF SUBSTANTIALLY INERT CONTACT MATERIAL AT TEMPERATURES OF1000-1200* F. AND SUBJECTING A MIXTURE OF THE REACTION PRODUCTS FROMSAID COKING PROCESS BOILING BELOW ABOUT 430* F., AND A NAPHTHA STOCKRICH IN NAPHTHENES TO TREATMENT IN CONTACT WITH A CHROMITE HYDROGENATIONCATALYST EFFECTIVE FOR THE CONVERSION OF DIOLEFINIC AND ACETYLENICCOMPOUNDS TO MONOOLEFINS BUT WHICH IS RELATIVELY INACTIVE FOR THEHYDROGENATION OF MONOOLEFINS TO PARAFFINS THEREBY SELECTIVELY CONVERTINGTHE DIOLEFINIC AND ACETYLENIC COMPONENTS TO MONOOLEFINS.